PNP transistor emitter region is heavily doped(p+) and base will be smaller in area.

Emitter-base region in forward biased conditions current is due to majority carriers by diffusion,since emitter is heavily doped so majority carries move easily to base region.

Base to collector region is reverse biased, the current only due to those carries who come across barrier by a Electrified i.e.drift current.
emitter diffuse majority carries but collector region collect by drift phenomenon.
the main stream of current here is majority carries current.i.e diffusion current.

Introduction:
In a PNP transistor operating in the active region, the main stream of current is the diffusion of holes. The active region is characterized by both the base-emitter junction and the base-collector junction being forward-biased. In this region, the transistor operates as an amplifier and is capable of providing current gain.

Explanation:
In order to understand why the main stream of current in a PNP transistor operating in the active region is the diffusion of holes, we need to look at the behavior of the different regions within the transistor.

Emitter Region:
The emitter region in a PNP transistor is heavily doped with a large number of majority charge carriers, which are holes in this case. Due to this heavy doping, the concentration of holes in the emitter region is much higher than in the base region.

Base Region:
The base region is lightly doped and serves as a barrier between the heavily doped emitter region and the lightly doped collector region. The concentration of holes in the base region is much lower compared to the emitter region.

Collector Region:
The collector region is also lightly doped and is responsible for collecting the majority charge carriers from the base region. In the case of a PNP transistor, the majority charge carriers are electrons.

Operation in Active Region:
When the base-emitter junction is forward-biased, the positive terminal of the voltage source is connected to the base terminal and the negative terminal is connected to the emitter terminal. This forward biasing creates a potential difference across the base-emitter junction, allowing the majority charge carriers (holes) from the emitter region to diffuse into the base region.

Due to the concentration gradient, the holes diffuse from the emitter region into the base region. These diffusing holes constitute the main stream of current in the active region of a PNP transistor.

Conclusion:
In a PNP transistor operating in the active region, the main stream of current is the diffusion of holes. The forward biasing of the base-emitter junction allows the majority charge carriers (holes) from the heavily doped emitter region to diffuse into the lightly doped base region. This diffusion of holes constitutes the main current flow in the active region.